The presence of an
estrogen-regulated protein with 24,000 molecular weight has been studied in 47 patients with
endometrial carcinomas and in 29 patients with cervical
carcinomas in order to correlate its presence with that of
estrogen receptors (ERs) and
progesterone receptors (PgRs). In the cytosol
tumor samples the Mr 24,000
protein was detected by the Western blot technique using a
monoclonal antibody (C11), while the presence of ER and PgR was studied by the one-point
dextran-coated
charcoal assay. In the
tumor tissue sections immunohistochemistry was applied to detect Mr 24,000
protein, ER, and PgR; in these cases monoclonal antireceptor
antibodies (H222 and mPRI) were used to localize the receptor
proteins. In endometrial and endocervical
adenocarcinomas the presence of Mr 24,000
protein correlated significantly with that of ER (P less than or equal to 0.05) in the cytosol samples; when the evaluation was performed in the
tumor sections, the presence of Mr 24,000
protein correlated with that of ER (P less than or equal to 0.005) and PgR (P less than or equal to 0.05) as well. The study also showed that almost 70% of the well-differentiated
adenocarcinomas had ER, PgR, and Mr 24,000
protein. In 25% of the endometrial
adenocarcinomas examined the
tumors were associated with normal, proliferative, and hyperplastic endometrium; in these cases the presence of ER, PgR, and Mr 24,000
protein was evaluated by immunohistochemistry in the malignant and nonmalignant endometrium. On the other hand, there was a lack of correlation between Mr 24,000
protein, ER, and PgR in the
squamous carcinomas of the uterine cervix and in the endometrial
adenocarcinomas with squamous cells. In most of these cases the
tumors lacked ER and PgR although 80% of them contained the Mr 24,000
protein to a variable degree. It is suggested that Mr 24,000
protein is involved in growth and differentiation (the Mr 24,000
protein is a
heat shock protein) and that the gene coding of this
protein is under hormonal control only in those tissues where growth and differentiation are strongly hormonally controlled (breast and endometrium).